just because it isnt listed on the package doesnt mean it isnt in there. they dont legally have to list it on the packaging because it is not a fertiliser licenced for production of food. House and garden is licenced for use with ornamentals, e.g flowers etc. go have a look how many PGR's are used in the production of things like cotton. because nobody is eating it you can pretty much add whatever you like.
honestly i cant prove its in there but having grown with a bunch of other PGR's over the years back before we new it was bad and when yield was king above all else. i would say it takes a PGR to get that kind of response from a plant.
if it looks like a duck, walks like a duck and quacks like a duck, its probably a duck